In signal processing, because much time is required for processing a great quantity of data solely by software, it has been desireable to fabricate integrated circuit chips which can be used for signal processing. Signal sorting is one of the most widely used methods for data processing and special computation.
A sorting circuit for signal sorting is disclosed by O. Vainio, Y. Neuvo, and S. Butner in "Sorter Based Signal Processor-A Versatile Tool for Median Type Filter Implementations", VLSI Signal Processing, IEEE. PRESS PP. 1610172, 1988. However, conventional sorting circuits, which are embodied by logic circuits, have high reliability but many drawbacks in actually processing a signal and in being used with other circuits. The drawbacks mainly result because of the complexity of the conventional sorting circuits.